EP1761381B1 - Fireproof glazing - Google Patents

Description

The present invention relates to fireproof glazing.

More specifically, the invention relates to glazings comprising one or more intumescent layers.

Fire protection glazing of this type must meet well-defined specifications, including standards such as European standards EN 1363-1 and 1364-1 for walls, or 1634-1 for doors and windows. These characteristics are of course aimed at the properties of fire resistance, but to these fundamental characteristics of the glazing in question must be added others which are fixed by the known modes of manufacture, or by the requirements of the users.

One way of constructing these glazings is to assemble several sheets of glass separated by layers of intumescent materials. The latter are most often composed of hydrated alkali silicates. These materials under the effect of heat expand by forming a foam opaque to radiation, foam that keeps the glass walls in position even when the latter are fragmented under the effect of heat.

Intumescent layers in addition to their fire resistance properties must meet a series of requirements. They must especially be perfectly transparent, have no defects such as the presence of bubbles or a veil diffusing light. Such defects are inherent in the compounds constituting these layers and in the modes of preparation of these layers.

The usual mode of preparation of the hydrated alkali silicate layers comprises the formation of a solution of these compounds, the deposition on a glass sheet of a uniformly distributed quantity of this solution to constitute a film of the order of a few millimeters d thickness, then drying this film up to to form a transparent solid material. These drying operations are the subject of delicate techniques and difficult to master perfectly. In particular, obtaining a layer free of bubbles usually passes through prolonged drying. This drying is longer as the layer is thicker. In fact, the drying time increases much more than proportionally to the thickness. For this reason it is preferable not to increase too much the thickness of the intumescent layer or layers of these glazings.

Moreover, the effectiveness of the layer, as regards its fireproof properties, depends directly on the thickness thereof. To obtain fireproof properties meeting the most usual requirements, a thickness of several millimeters is necessary. But experience shows that beyond 2 or 3mm thick, the drying time becomes industrially crippling. For these reasons, it is customary to distribute the intumescent material in several layers each of more limited thickness. These layers are separated by as many sheets of glass.

If the fractionation of the intumescent material facilitates drying, however, it leads to a multiplication of elements constituting the glazing, resulting in a possible additional cost.

To the constraints indicated above are added others concerning the use of glass sheets of large dimensions. To meet all the demands glazings are produced in panels of more than two meters out of three. These panels are then cut to the most varied dimensions requested by customers. The handling of glass sheets of these dimensions during the manufacture of glazing is all the more inconvenient as the leaves are less thick.

The multiplication of glass sheets, which is induced by the need to distribute the mass of intumescent material in relatively thin layers, therefore leads quickly to very heavy assemblies so far and moreover relatively thick. This creates a number of constraints with respect to the frames in which these windows can be inserted.

The fire-resistant glazings according to the invention are as indicated in claim 1. These glazings withstand some of the most severe fireproofing, namely combining sealing and insulation for very long periods of 90 minutes. (EI90) or even 120 minutes (EI120), and are in thicknesses respectively at most equal to 37 and 54mm.

In addition to the fire resistance properties, the glazing must also offer mechanical qualities for "normal" use conditions, ie out of fire exposure. These depend closely on the use that is made of them, but even for those that do not require very particular performances, a minimum is required, which very small glass thicknesses do not make it possible to satisfy. In order to improve the mechanical properties of these glazings, two types of solutions have been proposed if the solution of using reinforced glasses is not used, since the latter do not offer the optical quality required. The first solution is to modify the glasses used. An increase in the thickness makes it possible to improve the mechanical strength but has the counterpart of a greater total thickness. This tendency is all the less desirable as the need to reinforce the structures appears essentially for less fire-resistant glazings, and consequently which must be the least thick. An increase in the thickness of the glass sheets is then particularly sensitive on the structure. In other words, the improvement of the mechanical resistance through the presence of one or more sheets of glass of greater thickness, is not proportional to the resulting effect in terms of fire resistance for these structures most light. Another way to improve resistance
Mechanical consists of making assemblies comprising one or more interlayers of plastic material such as PVB or EVA. These leaves give improved mechanical strength, but their presence in relatively light structures is generally accompanied by a degradation of the fire resistance. In these lightweight structures, these synthetic products are too exposed to rapid destruction under the effect of heat. For this reason, if they are well used in heavier structures, where their position at the heart of these structures, makes them less exposed to decomposition temperatures, their use in light structures is not without risk for their fire performance. Conversely, in more complex structures, the presence of spacers can improve fire performance by limiting the risks of what is referred to as "monolithic breakage". Under this name is meant the rupture of leaves subjected to fire, by large sections, resulting in premature destruction, before each of the constituents, and in particular the intumescent layers have been able to play their full role.

The inventors have therefore endeavored to produce glazing that makes it possible to meet the various requirements mentioned above, requirements as indicated which are the subject of partial solutions often contrary.

To achieve the desired properties, the inventors have made glazings of complex structure comprising alternating intumescent layers based on hydrated alkali silicates on the one hand, and glass sheets on the other hand. The intumescent material layers of the glazings according to the invention do not have a thickness greater than 2.0 mm, and not less than 1.4 mm. Advantageously, the thickness of the intumescent layers is between 1.5 and 1.8 mm.

For thicknesses greater than 2.0 mm the optical qualities are very difficult to obtain under conditions of preparation time, especially drying, industrially acceptable. Less than 1.4mm, the number of layers required, and consequently the number of glass sheets used in the composition of the final glazing, are disadvantageous from the point of view of the cost of these windows, and moreover, the thickness of the assembly does not meet the usual constraints.

For these thicknesses of intumescent material, however, it becomes necessary to multiply the number of layers. To meet the requirements it is necessary to associate these layers with sheets of glass in number and thickness well established.

The glazings according to the invention combine a number of glass sheets at least equal to that of the intumescent layers present in this glazing.

When these two numbers are equal, the structure has this particular, the two outer faces must necessarily be those of glass sheets, two intumescent layers are contiguous to each other. This arrangement is not contrary to the requirements indicated above with regard to the upper limit of the thicknesses that can be obtained by drying. The assembly which leads to attaching two layers of intumescent material occurs in effect once the drying achieved. Of course in this operation, the final product comprises an intumescent layer which is then double, and the thickness limits indicated above are also doubled for this layer formed by joining two previously dried layers. Thus, the "double" layers can be up to 4mm thick.

It should be noted that these double layers keep track of how they are obtained. The assembly of two intumescent layers, does not completely disappear the features that attach to the surface of these layers. Drying leads to the formation of a particularly dry "skin". This skin is found in the heart of the intumescent layer formed during this assembly. A detailed analysis of the products makes it possible to distinguish this type of assembly from a single layer of the same thickness.

When the number of layers and sheets of glass is identical, the glazings according to the invention comprise at least two assemblies formed of two contiguous layers, and moreover as many sheets of interlayer material minus one that there are "double" layers. It is indeed possible to multiply the double layers, but this leads to then assemble sheets of glass by means of interlayer sheets of the type used for the traditional constitution of laminated glazing. These include polyvinylbutyral sheet or ethylene vinyl acetate.

When the number of glass sheets is equal to that of the intumescent layers, the thickness of the glass sheets must remain within certain limits. In practice these sheets are not more than 4mm thick and preferably not more than 3.5mm. Preferably this thickness is not greater than 3.1mm.

In glazings meeting these conditions, the thickness of the glass sheets may be uniform. This procedure has the advantage of allowing the constitution of glazing by means of all identical elements. However, it is possible to assemble from different elements. For products that must remain relatively light, the presence of at least one sheet of glass of greater thickness can offer advantageous mechanical characteristics without causing an inadequate total thickness.

When the number of glass sheets is greater than that of the intumescent layers, in order to maintain the conditions relating to the total thickness of the glass it is necessary that the glass sheets, or at least those in number equal to that of the intumescent layers, are Thin well limited. According to the invention, when the number of glass sheets is greater than that of the intumescent layers, at least a number equal to that of these layers has a thickness which is not greater than 2.5 mm. Preferably this thickness is not greater than 2.3 mm and advantageously not greater than 2.1 mm.

Taking advantage of the fact that the thickness of a large number of glass sheets of the assembly is relatively limited, it is possible, while maintaining a total thickness suitable, to have at least one glass sheet thicker to stiffen and improve the strength of the assembly. The thickness of this additional sheet is nevertheless limited so as not to increase the weight and the thickness of the assembly excessively. It is advantageously 5 mm and more, and preferably 6 mm and more. The thickness of this sheet does not normally exceed 10mm.

The additional sheet or sheets may be of the monolithic type. They may also be in the form of a laminate consisting of two sheets of glass traditionally joined by an interlayer sheet of a plastic material. For this purpose, a sheet of PVB (polyvinyl butyral) or EVA is usually used. The use of a laminate gives the glass mechanical qualities well known. As indicated above, the use of laminated glasses is preferably reserved for implementations in which the plastic sheet is not likely to be too directly exposed to fire. It is therefore relatively complex structures, or structures in which the laminated panel is located asymmetrically on the side that is not likely to be exposed to fire.

When a thicker monolithic sheet is part of the structure, its position is not as critical as for the laminate. However, it is preferably located on the side exposed to fire. Experience shows that even when subjected to thermal shock leading to its rupture, the protection of the underlying intumescent layer is better ensured. The thermal inertia of this thicker sheet leads in particular to a more homogeneous distribution of the heat and consequently to a more uniform expansion of this layer, avoiding the premature tearing of the pieces of the broken sheet.

The choice of the location of the thicker leaf or laminate may be guided by other considerations. In particular, there is a very important need to standardize as much as possible the elements that go into the constitution of these structures as explained below.

As in assemblies comprising an equal number of glass sheets and intumescent layers, it is possible to join several intumescent layers in structures comprising additional monolithic or laminated glass sheets. The lamination may also relate to the glass sheets meeting the thickness criteria indicated above.

If, in principle, it is possible to have glass sheets and intumescent layers associated with them, of different thicknesses and even of different natures, in practice, it is desirable to form these assemblies from a number of distinct elements as small as possible. For this reason, the glazings according to the invention advantageously consist of sheets of glass which, with the possible exception of the sheet, or so-called additional sheets, are all of the same thickness. In the same way, the intumescent layers associated with these glass sheets are advantageously of the same composition and of the same thickness.

These choices make it possible to constitute the glazings by means of a single type of product formed of a glass sheet on which a layer of intumescent material has been cast and then dried. This standardization of production is a factor of economy. To accentuate this trend, efforts are still being made to ensure that the same elementary glass sheet / intumescent layer combinations are used for constituting glazing of different categories. To pass from one to the other, it is advantageous to simply associate a different number of these combined elements, a glazing with a higher fire resistance then corresponding to a greater number of these elements.

In the assembly process of the elements, it is also possible to partially assemble modular units, preceding the final assembly. As an indication, as will be detailed in the implementation examples, modules comprising two, three or four identical glass sheets, each carrying a layer of alkali silicate previously dried, can be combined by the usual treatment techniques in this case. domain, basically a collage by steaming under pressure of these sheets to form modules. These modules comprise a face constituted by a glass sheet, and a face having the intumescent layer. These modules can then be associated with either a sheet constituting the second face of the glazing unit, or by means of a sheet (monolithic or laminated) to a module which may be different, but which is preferably identical. Under these conditions (assembly of two identical modules) the structure is symmetrical and the possibly different thickness of glass, or laminated glass, is in the middle of the structure.

The glass sheets used according to the invention are most usually made of conventional silico-soda-lime glass. They may optionally be replaced in whole or in part by glass sheets having improved mechanical and thermal characteristics. It may be in particular glass sheets having a lower coefficient of expansion, thus ensuring better resistance to deformation under the effect of heat. These are well known compositions, for example borosilicates. Glasses of this type advantageously have an expansion coefficient which is not greater than 7.5 × 10 ^-6 / ° C.

The sheets may also have undergone treatments, in particular of the chemical or thermal quenching type, to give them stresses favoring their mechanical strength.

• la figure 1 représente un composant élémentaire des vitrages selon l'invention ;
• la figure 2 montre le principe d'assemblage pour constituer les vitrages à partir des composants élémentaires ;
• les figures 3 et 4 illustrent deux modes de réalisation d'un vitrage selon l'invention formés uniquement de composés élémentaires ;
• les figures 5, 6 et 7 montrent deux modes de réalisation de vitrages selon l'invention comportant en plus des composants élémentaires des feuilles de verre additionnelles ;
• les figures 8 et 9 représentent d'autres modes de réalisation de vitrages selon l'invention comportant des assemblages feuilletés dans leur structure.

The invention is described in detail in the following in various examples of implementation and with reference to the attached plates in which:

• the figure 1 represents a basic component of glazing according to the invention;
• the figure 2 shows the principle of assembly to constitute glazing from elementary components;
• the Figures 3 and 4 illustrate two embodiments of a glazing according to the invention formed solely of elementary compounds;
• the figures 5 , 6 and 7 show two embodiments of glazing according to the invention further comprising elementary components additional glass sheets;
• the Figures 8 and 9 represent other embodiments of glazing according to the invention comprising laminated assemblies in their structure.

As indicated, the production of the glazings contemplated by the invention requires the formation of a solid and transparent hydrated alkali silicate layer from a solution which is gradually dried. The formation of this layer and its drying are carried out directly on a glass sheet. The basic element (a) as schematized in figure 1 comprises a glass sheet (1) on which there is a previously partially dried alkaline silicate layer (2).

The formation of glazing according to the invention involves the assembly of several basic elements (a), as shown in FIG. figure 2 . The assembled structure comprises a succession of glass sheets (1) and layers of hydrated alkali silicate (2). The number of basic elements is even higher than the fire resistance must be greater.

For the formation of fireproof glazing, it is of course necessary to ensure that the two outer faces are made of glass sheets. Assemblies as represented in the figure 2 are not enough. One way of producing the glazing thus consists in applying two layers of alkaline silicates hydrated on one another, as shown in FIGS. Figures 3 and 4 . The layers thus contiguous can be located at various locations in the structure. The figure 3 shows a glazing unit in which the last base element (a) is thus applied by its intumescent layer to the similar layer of the preceding element. The structure thus constituted only of basic elements comprises as many sheets of glass as hydrated alkali silicate layer, but two of the latter are gathered forming of course a layer of greater thickness (3). The glass sheet (4) of the last element here constituting the second external face of the glazing.

The bonding of the two intumescent layers, in addition to the thickness, is identifiable by the structure of these layers. Their mode of formation makes it possible to distinguish the surface exposed to drying from the remainder of the layer. The presence of two contiguous surfaces retains peculiarities in the heart of the layer formed of two elementary layers.

The position of the "double layer" can be located at all levels in the final structure. The figure 3 present this double layer completely off-center. The figure 4 shows the opposite double layer in the center of the glazing. The latter type is particularly obtained when one proceeds to the formation of glazing by assembling "modules" previously constituted themselves by the assembly of elementary components (a). In the example presented, each module consists of three basic elements (a).

This type of assembly can give rise to very varied combinations likely to respond to different modes of use.

In addition, the glazings according to the invention, apart from the basic elements (a), may also comprise other components. The Figures 5 to 9 illustrate different glazings with additional elements.

The figure 5 shows an assembly of a series of elements (a) to which an additional glass sheet is associated to "cover" the last hydrated alkali silicate layer. In the form presented the last sheet is of the same thickness as that of the elements (a). An identical structure can be obtained by assembling two modules themselves formed of several basic elements (a) by interposing between the two silicate layers of each of the two modules an additional glass sheet.

The use of relatively thin sheets and intumescent layers makes it possible to achieve even slightly thick glazing. Nevertheless, this choice leads to limiting the mechanical strength, in particular for the lightest structures. The thickness gain optionally makes it possible to complete the assemblies formed of elements (a) of small thickness by a substantially thicker glass sheet, in particular to achieve improved mechanical properties.

The Figures 6 and 7 , illustrate the constitution of glazings which comprise a glass sheet (6,7) thicker than that of the elements (a). To the figure 6 the thick sheet is centrally located between two modules each in the example comprising three elements (a). To the figure 7 , the thicker sheet (7) constitutes an outer face of the glazing.

The presence of a thick sheet is intended to enhance the mechanical strength of the glazing outside of the fire exposure, to meet the various requirements that may be those of glazing in their "ordinary" use and particularly when they come into the composition of partition, door, etc. For applications requiring even greater strength, particularly for glazing used in the facade, it may be advantageous to form assemblies comprising plastic interleaves, such as those used in laminated safety glazing. The interleaves in question are well known to glassmakers. This is most usually PVB (polyvinyl butyral) or EVA sheets. These transparent products allow the breaking of the glass sheets to maintain the fragments in position thus avoiding the dangers caused by the possible fall of these fragments. The sheet of organic material may further contain additives improving its fire resistance.

The Figures 8 and 9 illustrate two structures incorporating a plastic interlayer sheet (10). The formation of these structures is similar to those represented in Figures 6 and 7 , the thick sheet (7) being replaced by a laminated glass (11) comprising the interlayer (10).

The presence of the interlayer has advantages in addition to those concerning the impact resistance. The products in question constitute in particular a UV barrier which can lead to the aging of the intumescent layers. The aging of these layers can cause the appearance of a veil, or that of bubbles. UV protection is therefore particularly desirable for windows exposed to UV light such as façade glazing. In this case it is desirable to have the laminate on the side of the glazing most directly exposed to UV. Glazing of the type illustrated in the figure 9 is preferred to those in which the spacer sheet is in the core, as shown in FIG. figure 8 .

In all these examples, the leaves are of clear silico-soda-lime glass.

The intumescent layers consist of hydrated alkali silicate with an SiO ₂ / Na ₂ O molar ratio of 3.3. The initial solution deposited on the sheets before drying further comprises 7% by weight of glycerine and 0.5% by weight of TMHA (tetramethylammonium hydroxide) and 65% of water.

After drying in a ventilated oven and controlled hygrometric degree, the water content of the material is reduced to about 20%. Drying is achieved in a 24-hour cycle.

The sheets carrying the layers of hydrated alkali silicate are assembled by calendering or pre-bonding under vacuum, followed by steaming under pressure for 1 hour at 120 ° C.

We give in the following the composition of different fire-resistant glazings constituted such that they meet the requirements of the invention. In particular, the proposed glazings formed from basic elements possibly associated in modules whose meeting constitutes the complete structure, makes it possible to improve the overall production efficiency, the possible elimination of defective elements being limited to the single element of concerned and not to the complete glazing.

• chaque feuille de verre est indiquée par son épaisseur (en mm ;)
• chaque couche intumescente est notée par (/) ;
• chaque feuille intercalaire plastique de type PVB est notée par (:)

In the following, by convention, the different constituents are noted as follows:

• each sheet of glass is indicated by its thickness (in mm;)
• each intumescent layer is denoted by (/);
• each PVB plastic interlayer sheet is denoted by (:)

$$2/2/3/2/2:2/2/3/2/2$$

$$2/2/4/2/2:2/2/4/2/2$$

$$2/2/2//2:2//2/2/2$$

$$2/2//2/2:2/2//2/2$$

$$2//2/2/2:2/2/2//2$$

et $$3/3/3//3:3//3/3/3$$

$$3/3//3/3:3/3//3/3$$

$$3//3/3/3:3/3/3//3$$

The following glazings have been constituted. They correspond to assemblies of fire resistance EI90: $$2/2/2/2/2:2/2/2/2/2$$

$$2/2/3/2/2:2/2/3/2/2$$

$$2/2/4/2/2:2/2/4/2/2$$

$$2/2/2//2:2//2/2/2$$

$$2/2//2/2:2/2//2/2$$

$$2//2/2/2:2/2/2//2$$

and $$3/3/3//3:3//3/3/3$$

$$3/3//3/3:3/3//3/3$$

$$3//3/3/3:3/3/3//3$$

The test glazing (2) with the fire test is 100mn. This structure is particularly preferred, combining good properties with a limited total thickness.

The glazing tested was of dimensions 1200x2300mm. The interlayer sheet is 0.76mm PVB.

The amount of solution deposited on each glass sheet before drying was 4.2 liter / m ² . After drying each intumescent layer was 1.56mm thick. The total thickness of the glazing was 34.9mm.

The trial glazing (7) of the same dimensions as the previous one, with fewer glass sheets, withstands the experiment a little longer. Fire resistance is 90 minutes.

For this glazing the same starting composition is deposited on the glass sheets at a rate of 4 liter / m ² . After drying each intumescent layer is 1.43mm thick. The total thickness of the glazing is 35mm.

$$2/2/3/2/2:2/2/3/2/2:2/2/3/2/2$$

$$2/2/2/2/2/2:2/2/2/2/2/2$$

$$2/2/2/2/2/2/2:2/2/2/2/2/2/2$$

$$2/2/2//2:2//2/2/2:2//2/2/2$$

$$2/2//2/2:2/2//2/2:2/2//2/2$$

et $$3/3/3//3:3/3//3/3:3//3/3/3$$

$$3//3/3/3:3/3//3/3:3/3/3//3$$

$$3/3/3/3/3//3:3//3/3/3/3/3$$

$$3/3/3//3:3//3/3/3:3//3/3/3$$

The following glazings have been made which correspond to assemblies of fire resistance EI 120: $$2/2/2/2/2:2/2/2/2/2:2/2/2/2/2$$

$$2/2/3/2/2:2/2/3/2/2:2/2/3/2/2$$

$$2/2/2/2/2/2:2/2/2/2/2/2$$

$$2/2/2/2/2/2/2:2/2/2/2/2/2/2$$

$$2/2/2//2:2//2/2/2:2//2/2/2$$

$$2/2//2/2:2/2//2/2:2/2//2/2$$

and $$3/3/3//3:3/3//3/3:3//3/3/3$$

$$3//3/3/3:3/3//3/3:3/3/3//3$$

$$3/3/3/3/3//3:3//3/3/3/3/3$$

$$3/3/3//3:3//3/3/3:3//3/3/3$$

The test glazing (11) withstands the fire test for 129 minutes. As before, this structure is particularly advantageous which offers both good anti-fire properties associated with a well-controlled thickness.

This glazing is 1200x2000mm.

Among the structures (16) to (19), the structure 19 has the advantage of consisting entirely of a single module 3/3/3 // 3 repeated three times in the assembly with the two interlayers. Production is therefore largely simplified compared to other structures.

The amount of solution deposited on each glass sheet before drying was 4.2 liter / m ² . After drying each intumescent layer was 1.56mm thick. The total thickness of the glazing was 53mm.

The trial glazing (16) is of the same dimensions as the previous one. Its fire resistance is 123mn.

For this glazing the same starting composition is deposited on the glass sheets at a rate of 4 liter / m ² . After drying each intumescent layer is 1.45mm thick. The total thickness of the glazing is 53.3mm.

Claims (12)

1. Fire-resistant glazing classified either as EI 90 or EI 120 according to Standards EN 1363-1 and 1364-1 for tightness and insulation, formed of a laminated assembly comprising more than four glass sheets and layers of intumescent material based on hydrated alkali metal silicates, in which the layers of intumescent material each have a thickness of 1.4 to 2 mm, when each layer is separated by a glass sheet, it being possible, if appropriate, for layers of this material to be placed side by side in pairs, and optionally comprising, in addition, one or more sheets of interlayer material between two glass sheets, and in which:

   ▪ either the number of glass sheets is equal to the number of intumescent layers, the glazing comprising at least two assemblies formed of two layers placed side by side, and at least as many interlayer sheets minus one as there are of assemblies of layers placed side by side, the glass sheets, in number equal to that of the intumescent layers, each having a thickness at most equal to 4 mm

   ▪ or the number of glass sheets is greater than that of the intumescent layers, a number of glass sheets equal to that of the intumescent layers exhibiting a thickness at most equal to 2.5 mm

   the glazing exhibiting a total thickness at most equal to:

   ▪ 37 mm for EI 90

   ▪ 54 mm for EI 120.
2. Fire-resistant glazing according to Claim 1, in which the number of intumescent layers is equal to the number of glass sheets, and the glazing comprises at least two assemblies of layers placed side by side, each of the glass sheets having a thickness at most equal to 3.1 mm.
3. Glazing according to Claim 2, in which the glass sheets, in number equal to that of the intumescent layers, have a thickness at most equal to 2.3 mm.
4. Glazing according to Claim 3, in which the glass sheets, in number equal to that of the intumescent layers, have a thickness at most equal to 2.1 mm.
5. Glazing according to one of the preceding claims, in which the layers of intumescent material have a thickness of between 1.5 and 1.8 mm.
6. Glazing according to Claim 1, in which the number of glass sheets is greater than that of the intumescent layers, which glazing comprises at least one glass sheet with a thickness at least equal to 5 mm.
7. Glazing according to Claim 6, comprising at least one glass sheet with a thickness at least equal to 6 mm.
8. Glazing according to Claim 1, comprising at least four layers of intumescent material and the same number of glass sheets plus two, two of the glass sheets being joined together by means of an interlayer sheet of a plastic material of PVB or EVA type.
9. Glazing according to Claim 1, corresponding to the standards for tightness and insulation glazings EI 90, the composition of which, based on unitary elements formed of a 2 mm glass sheet, is one of the following:

   2/2/2/2/2 : 2/2/2/2/2

   2/2/3/2/2 : 2/2/3/2/2

   2/2/4/2/2 : 2/2/4/2/2

   2/2/2//2 : 2//2/2/2

   2/2//2/2 : 2/2//2/2

   2//2/2/2 : 2/2/2//2

   the different constituents being denoted in the following way:

   ▪ each glass sheet is indicated by its thickness (in mm);

   ▪ each intumescent layer is denoted by (/);

   ▪ each plastic interlayer sheet of PVB type is denoted by ( : ).
10. Glazing according to Claim 1, corresponding to the standards for tightness and insulation glazings EI 90, the composition of which, based on unitary elements formed of a 3 mm glass sheet, is one of the following:

    3/3/3//3 : 3//3/3/3

    3/3//3/3 : 3/3//3/3

    3//3/3/3 : 3/3/3//3

    the different constituents being denoted in the following way:

    ▪ each glass sheet is indicated by its thickness (in mm);

    ▪ each intumescent layer is denoted by (/);

    ▪ each plastic interlayer sheet of PVB type is denoted by (:).
11. Glazing according to Claim 1, corresponding to the standards for tightness and insulation glazings EI 120, the composition of which, based on unitary elements formed of a 2 mm glass sheet, is one of the following:

    2/2/2/2/2 : 2/2/2/2/2 : 2/2/2/2/2

    2/2/3/2/2 : 2/2/3/2/2 : 2/2/3/2/2

    2/2/2/2/2/2 : 2/2/2/2/2/2

    2/2/2/2/2/2/2 : 2/2/2/2/2/2/2

    2/2/2//2 : 2//2/2/2 : 2//2/2/2

    2/2//2/2 : 2/2//2/2 :2/2//2/2

    the different constituents being denoted in the following way:

    ▪ each glass sheet is indicated by its thickness (in mm);

    ▪ each intumescent layer is denoted by (/);

    ▪ each plastic interlayer sheet of PVB type is denoted by (:).
12. Glazing according to Claim 1, corresponding to the standards for tightness and insulation glazings EI 120, the composition of which, based on unitary elements formed of a 3 mm glass sheet, is one of the following:

    3/3/3//3 : 3/3//3/3 : 3//3/3/3

    3//3/3/3 : 3/3//3/3 : 3/3/3//3

    3/3/3/3/3//3 : 3//3/3/3/3/3

    the different constituents being denoted in the following way:

    ▪ each glass sheet is indicated by its thickness (in mm);

    ▪ each intumescent layer is denoted by (/);

    ▪ each plastic interlayer sheet of PVB type is denoted by (:).

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